可变长符号的联合信源信道与多维调制编译码方法研究

Based on the characteristics of deep space communication and mobie radio systems in resource constraint networks, there are the large scale loss, small scale fading and multi-path, In order to adapt various space communication environment constraints, joint coding/decoding and Multimodulation realizes the cooperation of Shannon source channel coding and Multimodulation, which realizing joint optimization to set up variable-length symbol joint iterative coding decoding architecture. So it is possible to increase the minimum Hamming distance between the seguence of channel codes and the minimum Euclidean distance between the variable-length symbol of signal constellation, which employing the source priori information from VLC tree as well as the signal constellation extrinsic information to obtain optimum decoding, do research on the joint source channel and modulation coding/decoding approach based on variable-length symbols, and the joint source channel and 2D-QPSK-TCM coding/decoding algorithm is proposed for resource constraint networks . Theoretically this research can guide the development of joint source channel and Multimodulation coding /decoding in our country.

针对深空通信和移动通信等资源有限网络，存在大尺度路径损耗、小尺度衰落和多径效应的恶劣空间传输环境，将香农信源、信道编码理论和多维调制相结合，联合优化设计,建立可变长符号的联合信源信道与调制的迭代编译码模型，用信源冗余增加信道码的最小汉明距离和用变长符号增加星座点间的欧式距离，使信源可变长码的剩余冗余在信道译码和在星座点上映射得到充分的利用，可以有效增加抗误码率。研究可变长符号的联合信源信道与调制编译码方法，设计并开发面向资源受限网络的联合信源信道与2D-QPSK-TCM调制编译码算法，为我国的联合信源信道与调制编译码提供理论依据和技术支持。

本项目针对深空通信和移动通信等资源有限网络，存在大尺度路径损耗、小尺度衰落和多径效应的恶劣空间传输环境，将香农信源、信道编码理论和多维调制相结合，对可变长符号的联合信源信道与多维调制编译码方法开展了研究。从调制与星座映射方案的优化入手，研究并建立了联合信源信道和调制迭代编译码的优化模型; 利用符号信源的先验信息，提出了一种适用于可变长符号的联合编译码系统的调制方案，该方法在信源码字中引入受控冗余，对符号级多维调制映射规则进行优化设计，并同时对信道译码序列的自由汉明距离和调制符号序列的自由欧氏距离进行优化，使概率大的符号对应的星座点与其他符号对应的星座点间的最小欧氏距离尽量大，而概率小的符号对应的星座点与其他符号对应的星座点间的最小欧氏距离小。利用这种分级映射规则，提高了抗误码性能。在可变长符号的联合编译码系统的调制方案的基础上，提出了一种可变长符号的联合信源信道与多维调制编译码系统，该系统能够增大译码路径的自由汉明距离和调制符号序列的自由欧氏距离，在不增加额外信道冗余的情况下实现低译码复杂度和高编码增益，提高系统的整体传输性能。针对常规星座映射优化算法复杂度高，且随着调制阶数的增大呈指数增长的问题，提出了一种适用于高阶调制的掺杂BICM-ID系统的8PSK星座映射优化算法。建立了联合信源信道与调制编译码仿真实验平台。为我国的联合信源信道与调制编译码提供了理论依据和技术支持。